A police officer who felt forced to resign after becoming a mother was offered help to carry on with her duties, a tribunal heard.

Pauline Sweeney, a highly respected detective constable based in Brighton, has accused Sussex Police of sexual discrimination and is claiming compensation.

Detective Superintendent Chris Gillings, head of the major crime branch at Sussex Police, said he had done everything he could to help Ms Sweeney juggle being a mother and a detective.

The elite unit deals with serious crimes such as murder and rape.

When crimes take place on call, detectives are called and told to get to the scene within two hours.

Because she was a part-time officer, Ms Sweeney, 37, from Heathfield, would have had to work once every eight weeks instead of once a month.

The tribunal earlier heard Ms Sweeney refused to be on call one weekend in eight because of childcare difficulties after agreeing to work part-time for 20 hours over two days a week.

Mr Gillings said he could not exclude her from on-call duties because it would not be fair on other colleagues.

He suspended her on-call duties for a year to give her time to arrange childcare but this caused complaints from colleagues.

He said: "If I allow one officer not to do call-out weekends I have to provide the same amount of cover with the remaining 23 officers."

He said he was determined to keep Ms Sweeney in the unit, adding: "She is a first-class officer - I wouldn't dispute that in any way. Her performance is not and has never been an issue."

Mr Gillings said the unit was often short of cover because officers were seconded to other units to work on investigations.

In one example a detective worked 12 days in a row so a colleague could go to a wedding. Ms Sweeney offered to be on call for weekdays and emailed a list of dates she was available but Mr Gillings said she had to accept the call-out dates on the rota and then switch with colleagues if the dates were inconvenient.

Eventually he said if she did not accept on-call duties, she would have to go to another department.

Ms Sweeney, 37, resigned in February this year.

At the tribunal, held in Brighton, Ms Sweeney's line manager, Detective Sergeant Paul Sellings, said it was essential to have officers available for call-out.

He said: "There was an incident recently where if the on-call officers had not gone out a murderer would not have been arrested and there was another incident where a child would have been killed."

Mr Sellings admitted he had received little equal opportunities training from Sussex Police and had sought advice from his wife, who works part-time at Marks and Spencer, when dealing with the issue.

The inquest heard that Sussex Police was still updating its policies over discrimination because of legislation that came into force in December 2003, which banned discrimination arising from a person's religion or sexual orientation.

Ms Sweeney's solicitor said because the policy made it impossible for her to stay in the unit it was "indirect discrimination".

She said the force should have a more flexible rota system where people looking after children could be on call at times that suited them.

Mr Sellings and Mr Gillings said this would have created an administrative nightmare.

The tribunal closed yesterday and a judgement will be passed in about two weeks.